A Cochrane review included 10 studies with a total of 3760 subjects. Pharmacotherapy was used as part of the interventions in 3 trials. 5 studies included behavioural support in the intervention, 4 included self-help therapy, and the remaining study had arms which included behavioural support and arms which included self-help therapy. 9 studies reported smoking abstinence at either 6 month follow-up, 12 month follow-up, or both, and the remaining trial reported cigarettes per day over seven days at 6, 9, and 12 month follow-ups. Abstinence was verified in 8 studies, by either expired carbon monoxide, saliva cotinine, saliva thiocyanate, or asking a relative or friend to confirm the participant had stopped smoking. Neither reduction or abrupt quitting had superior abstinence rates when all the studies were combined (RR 0.94, 95% CI 0.79 to 1.13), whether pharmacotherapy was used (RR 0.87, 95% CI 0.65 to 1.22), or not (RR 0.97, 95% CI 0.78 to 1.21), whether studies included behavioural support (RR 0.87, 95% CI 0.64 to 1.17) or self-help therapy (RR 0.98, 95% CI 0.78 to1.23).